Modern inventory systems, such as those in mail-order warehouses, airport luggage systems, and custom-order manufacturing facilities, face significant challenges in responding to requests for inventory items. In inventory systems tasked with responding to large numbers of diverse inventory requests, slow responses to inventory requests may result in an ever-increasing backlog of inventory requests. Furthermore, in inventory systems encompassing substantial amounts of physical space, response times for inventory requests may depend heavily on the storage spaces of the requested inventory items within the inventory system.